1. Technical Field
This invention relates to air/smoke/fire dampers. In particular, it relates to dampers which can be controlled to be set and reset (i.e., closed and opened) locally or remotely under power, and which seal the damper under pressure when the damper blades are in the closed position; and which can be operated to be partially closed in order to modulate air flow and pressure levels.
2. Background Art
Multi-blade non-butterfly type dampers and butterfly dampers, which can be closed automatically upon actuation by a heat-sensitive or other device are well-known in the art. Some such dampers snap closed under either their own weight (i.e., gravity), or by mechanical force provided by springs. As the art developed, external controls were devised to activate these dampers. Further, controls were also developed to cause the damper to be reset, that is, to be reopened to a ready position for heat responsive actuation in the event of fire or smoke conditions. See, for example, U.S. Pat. Nos. 4,301,569; 4,442,862; 5,533,929; 5,728,001 and Re. 32,362.
A disadvantage of these prior art dampers is that they typically have imperfect release means. As a result, a substantial amount of smoke and even flames may pass through the damper; often before it is activated. It would be advantageous to have a damper system that could be activated more reliably in advance of the fire or smoke passing through the system, to more effectively prevent either from passing through the damper.
In addition to problems caused by complicated heat responsive closure means, dampers which are closed by gravity or spring driven devices do not always form an effective positive seal. As a result, even though the damper may be in the closed position, smoke and flames may pass through the damper and spread to other parts of the building. Thus, it would be desirable to have dampers that form a more effective seal, rather than merely temporarily containing either the fire or the progress of smoke.
Also, if the blades are pivoted on their longitudinal centers, the air and heat does not help to keep the blade seals shut. Rather, pressure on one side of the pivot axis of the blade tends to force it open, while pressure on the other tends to force it closed. It is, therefore, desirable to have a pivoted blade damper which is forced to an even tighter closed and sealed condition under pressure.
It is further desirable to have a damper system in which the damper can be partially closed or opened, in order to modulate the pressure in the system. For example, it may be desirable to have more pressure in one room than another and to be able to adjust the opening in the damper, say for example remotely, so as to affect the amount of air passing through it.
The prior art has failed to provide a damper which can be powered closed well before advancing smoke and fire arrives and have failsafe spring closure on power failure, which creates an effective seal; which can be sealed rapidly by a powered drive mechanism; and further which can be partially opened and closed to modulate the pressure in the system in which the damper is used. Also, the prior art does not have a simple two blade end pivoting damper, with a direct drive linkage (for round and rectangular dampers).
My invention comprises, among other things, a damper assembly in which operation of the damper blades is controlled by an electric powered actuator having a lead screw shaft. The actuator drives an operator means attached to the damper blades. The actuator causes cycling of the damper blades to move them between an open and a closed position, and/or causes them to be set in intermediate positions to set up controlled pressure environments by modulating the air flow through the damper.
In another preferred embodiment, a DC motor powered actuator drives the lead screw shaft to cycle the damper blades between the open, closed and intermediate positions.
In another embodiment, the actuator is self-controlled by a heat responsive device.
Also, a remote control system can communicate with the damper controls via a hard wired connection, or alternatively, via radio transmission.
This configuration provides for a better seal in the case of the fully closed position of the blades. In particular, the powered actuation lead screw shaft provides sufficient force to operate against heated air flow and to seal the damper tightly; which, in turn, prevents both smoke and fire from easily passing through the damper.
This design lends itself more readily to round or oval duct configurations.
My invention comprises an electric power operated damper assembly, comprising:
a damper, having:
a damper frame and
at least one damper blade pivotally attached to the damper frame, to regulate the air
flow through the damper frame by movement of the blade;
an operator means engaging the damper blade for moving the blade in response to movement of the operator means; and
an electric powered actuator means, having a lead screw shaft powered for rotation about its axis; the electric powered actuator means engaging the operator means to cause the operator means to move the damper blade in response to movement of the actuator means.
It further comprises a powered operated damper assembly as described above, wherein the electric powered actuator means has an electric motor which is a DC stepper motor.
It further comprises an electric power operated damper assembly, wherein the electric powered actuator means is a cycling means for moving the lead screw shaft and causing the damper blade to move and cycle between various positions to modulate the air flow through the damper.
It further comprises an electric power operated damper assembly, wherein the powered actuator means further comprises a linkage means having a first portion thereof engaging the lead screw shaft to travel therealong in response to axial rotation of the shaft, and a second portion thereof engaging the operator means to move said damper blade in response to movement of said first portion alone said shaft.
It further comprises an electric power operated damper assembly wherein the first portion of the linkage means has a nut engaging the lead screw shaft to travel therealong.
It further comprises a electric power operated assembly, wherein the first portion of the linkage means has a gear mounted about the lead screw shaft; and the powered actuator means further comprises a solenoid means having a solenoid having a solenoid shaft movable to an extended and a retracted position; said solenoid being mounted in juxtaposition to said gear, so that in the extended position said solenoid shaft engages said gear and in the retracted position said solenoid shaft does not engage said gear, whereby when said solenoid shaft engages said gear, said gear travels along said lead screw shaft upon rotation of said lead screw about its axis.
It further comprises an an electric power operated damper assembly, wherein the power actuator means further comprises linkage means having a first portion thereof engaging the lead screw shaft to travel thereon to response to axial rotation of the shaft, said first portion of the linking means having a nut as a part thereof; and said power actuated means further comprises means to engage said nut to prevent its rotation whereby said nut travels along said lead screw shaft upon rotation of said lead screw shaft; and said linkage means further comprises a second portion thereof engaging the operator means to move said damper blade in response to movement of said nut along said lead screw shaft.
It further comprises a power operated damper assembly, further comprising:
a first blade travel sensor means juxtaposed to the lead screw shaft such that said sensor means notifies the powered actuator when the movable shaft has moved the damper blades to a first position; and a second blade travel switch attached to the movable shaft such that it notifies the powered actuator when the movable shaft has moved the damper blades to a second position.
It further comprises an electric powered damper assembly, further comprising a thermal lock attached to the damper assembly such that it does not restrict movement of the damper blades in normal operating conditions and does not restrict the movement of the damper blades in high temperature conditions to prevent the damper blades from moving from a closed to an opened position.
It further comprises a method of controlling air flow by opening and closing dampers with an electric powered damper actuator means, including steps of:
using a damper to control flow through a conduit, including the steps of:
juxtaposing a damper frame to a conduit;
pivotally attaching at least one damper blade to the damper frame to provide a position to allow air flow through said frame and a position to restrict air flow therethrough;
attaching an operator means to said blade to move said blade in response to movement of said operator means;
attaching to the operator means, a powered actuator means having an electric motor including a motor shaft, and a lead screw shaft rotatable about its axis in response to rotation of the motor shaft,
such that when the lead screw shaft is moved it moves the damper blade between said positions.
It further comprises a method as described above, including the additional step of connecting a sensor to the powered actuator, the sensor having means to control activation of the powered actuator to control opening or closing of the damper when a sensed condition indicates that the damper should be opened or closed;
whereby the sensor controls air flow through the damper.
It further comprises a method as described above including the additional step of connecting a sensor to the powered actuator, the sensor having means to control activation of the powered actuator to control the position of the blades of the damper between opening or closing of the damper when a sensed condition indicates that the damper should be partially opened or closed;
whereby the sensor controls air flow through the damper.
It further comprises a method as described above, including the additional step of locating the sensor remotely from the damper;
whereby the sensor can activate the damper before a sensed condition triggering activation of the powered actuator reaches the damper.